Spark igniter for a plurality of gas burners

ABSTRACT

A spark ignition system for a plurality of gas burners providing for operation of a plurality of spark ignition circuits from one a.c. source, with each of the ignition circuits having a voltage multiplier feeding a pulsing circuit which in turn provides ignition pulses to the ignition electrodes, with an isolation diode between the voltage multiplier and pulsing circuit of each ignition circuit.

United States.Patent [191 7 Hewitt "1451 May 28,1974

[54] A IGNITER FOR APLURALITY 3,384,440 /19 3 Mayer .1 431/66 v GASBURNERS 3,529,910 j 9/1970- Potts et al 431/27 J 3,561,900 2/1971Walbridge 431/256 Inventor: William L yd L- C y, 1 $632,285 1/1972'Foster; 431/264 Calif. v 4 3,716,758 2/1973 Palazzetti 317/96 73 A -t" tv l sslgnee $322 g g L08 Primary Examiner-Velodymyr Y. Mayewsky vAttorney, Agent, or Firm-l-larris, Kern, Wallen & 22 F1led:- Sept.21,1973 Tinsley [21] Appl. No.: 399,368 H [57] 7 ABSTRACT v [52] US. Cl317/96, 315/183; 315/206, f park igni on system for a plurality of gasburners v 431/264 providing for operation of a plurality of sparkignition [51] Int. Cl. F23q 3/00 circuits from one as source, with eachof h ignition [58] Field of Search 317/79, 96; 315/183, 206, circuitshaving avoltage multiplier feeding a pulsing 315/241;'431/27, 66, 256,264, 266 circuit which in turn provides ignitionpulses to the igit 1 p Iv 1 nition electrodes, with an isolation diode between the [561'References Qitedvoltage-multiplierand pulsing circuit of each ignitionUNITED STATES PATENTS 1 i 3,045,148 7/1962 Mcllultyetal t..1....;..315/1811 SCluims, 1 Drawing Figure \1 n1 n1 1 i I 'l I I .gZf/t e .1 9 I1; m 1.. 10 I I W vvv 1r I 5, #1- ,e1 2 2e 4e r 1 we? t g? ifs/z v, r\ aWM '1 r 'r M 1 1N3; {a V 11 43 4'1v N 1: =1 I t o 1 44% ii/if. 4a 7 1!.J

7 '1' L in I )v I I: 49 t age pulse across a pair of electrodes at thegas burner.

The pulsing circuit generates the pulses which produce sparks betweenthe electrodes causing ignition of the gas at the burner. US. Pat. No.3,349,284 shows an earlier form of pulsing circuit. US. Pat. No.3,662,185 shows thepulsing circuit of 1.1.5. Pat. No. 3,377,125energized by a voltage multiplier in the form of a voltage triplerl v Itis preferable to operate the spark igniters from a low voltage acsource, typically by means of a step down transformer with the primaryconnected to the l l5 volt supply and with the secondary providinga 24volt output. The 24 volt systems eliminate many wiring DESCRIPTION OFTHE PREFERRE EMBODIMENT f Three spark ignition circuits 10, 11, 12 areconnected to power supply terminals 13, 1'4,which typically may beenergized from the secondary winding of a transformer. The circuits 10,11, 12 are identical and each includes a voltage quadrupler l7 and apulsing circuit 18, with the output of the pulsing circuit connected tothe electrodes of a'spark gap igniter 19.

. The voltage quadrupler 17 includes a capacitor 21 connected betweenterminal 13 and junction 22, and

another capacitor 23 connected between terminal 13 and junction 24. Adiode '25 is connected between junctions 22 and 26, and another diode 27is connected between junction 22 and terminal 14. A capacitor 28 isconnected between the junction 26 and the terminal 14'. A seriescombination of a diode 30 and a resistor 31 is connectedbetween thejunction 24 and the terminal 14, and another series combination of adiode 32 and a resistor 33 is connected between thejunction 24 and ajunction 34 which may be connected to circuit ground. The diodes and arepoled for conduction problems which must be handled using higher voltagesystems. Also, it is often desirable to operate a plurality of thesparkigniters from a'single source, i.'e., from a single step-downtransformer. However problems are encountered when a plurality of thespark igniters are connected to a single ac supply. Common feedbackpaths are created between units and the resulting interaction causes theenergygenerated in thevolt age multipliers to be continuously depleted.Accordingly, it is an object of the presentinvention to provide a newand improved spark ignition system particularly suited for operationwith a plurality of gas burners from a single ac supply. A furtherobject is to provide such a spark ignition system utilizing theconventional circuitry with a simple yet highlyeffectivemodificationwhich prevents energy stored in one. voltage multiplier;from being depleted by operation of related pulsing'circuits.

SUMMARY OF THE lNVENTlON" t The spark ignition system of the presentinvention incorporates a plurality of spark ignition circuits with theBRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawingillustrates a spark ignition system for three gas burners andincorporating the presently preferred embodiment of the invention.

in the same direction and the diodes 27' and 32 are poled for conduction.in the opposite direction. 1

The output of the quadrupler l7 is,developed.across a capacitor 40 atjunctions 41, 34 diode 42. I

In the pulsing circuit 18, the primary winding 44 of a high voltage stepup, transformer 45 is connected in serieswith the anode and cathode ofacontrolled recti fier 46 across the junctions 41, 34. A resistor 47 is'connected in series with a capacitor 48 at junctions 49 across thejunctions 41, 34. A gas discharge device such as aneon lamp 52 isconnected in series with resistors 53, 54 across junctions 49 and34,with the control electrode of the controlled rectifier 46 connected tothe junction 55 between resistors 53, 54. j In operation, the capacitor40 is charged from the voltagemultiplier, and the capacitor 48 ischarged from the voltagemultiplier through the resistor 47. When thecharge on thecapacitor 48 builds up to a predetermined value, thelamp'52conducts, discharging the cathrough another pacitor 48 throughthe resistors 53, 54 and raising the junction 49 through the secondary58 to circuit ground and prevents the capacitor 48 from charging to avalue sufficient .to fire the lamp 52 while the flame is present. If theflame goes out for some reason, the pulsing circuit automaticallyproduces the sparks at the igniter.

There is interaction between a plurality of the spark V igniters causingcontinuous depletion of energy from the voltage multipliers. Thisinteraction is a result of the characteristics of the controlledrectifier (SCR) 46. The SCR is a bistable semiconductor which can beswitched'from off to on and from on to off. When the voltage between theanode and cathode of the device is below the breakover point, currentthrough the SCR is extremely small and the device is effectively an openswitch. I

The SCR is turned on by the application of a current to'the gate orcontrol electrode of the SCR. The gate current has the effect oflowering the SCR breakover point. Once breakover point is exceeded, theSCR switches to its on state, and will remain on with no furtherapplication of gate current, until the current from anode to cathodedrops below holding current. When current between anode and cathodedrops below holding current, the SCR reverts back to its high impedanceoffstate. 1

if a pluralityof spark igniters are connected to a single step-downtransformer, energy stored in capacitors 28 and 40 will transfer fromone unit to another in such a way that a continuous holding current willbe maintained on all SCRs. This causes them to remain on continuously.When these SCRs remain on continuously,

. capacitors 28 and 40 which act as reservoirs when the SCRs are in theoff state, will not be permitted to store energy. Diode 42 which permitscurrent to flow in one direction only, will prevent the energy transferfrom one spark igniter unit to another, and therefore permit any SCR toturnoff when the energy in capacitor 40 is depleted' i Typical valuesfor the circuit may be:

1. In an electric spark i'ngition system for aplurality of gas burners,the combination of:

a pair of power supply terminals for connection to an ac. power source;and a plurality of spark ignition circuits, each comprising:

a voltage multiplier having input terminals connected to said powersupply terminals and having multiplier output'terminals, I

a pulsing circuit having input terminals for connection to a voltagesource and providing a pulse output to ignition electrodes of a gasburner, and

electriccircuit means connecting said pulsing unit input terminals tosaid multiplier output terminals with a unidirectional conducting devicein circuit between one multiplier output terminal and the correspondingpulsing circuit input terminal.

2; A system as defined in claim 1 wherein each of said voltagemultipliers is a voltage quadrupler.

3. A system as defined in claim 1 including three of said spark ignitioncircuits. r

4. A system as defined in claim 3 wherein each of said voltagemultipliers is a voltage quadrupler.

5. A'system as'defined in claim [wherein each of said voltagemultipliers includes:

a first capacitor and a first diode connected in series 'at a firstjunction between one of said power supply terminals and said onemultiplier output terminal,

a second capacitor connected between said one multiplier output terminaland the other of said power supply terminals, a

a second diode connected between said first junction and said otherpower supply terminal,

a third capacitor and a third diode connected in series at a secondjunction between said one power supply terminal and the other of saidmultiplier output terminals, and

a fourthdiode connected between said second junction and said otherpower supply terminal. with said first and fourth diodes and saidunidirectional conducting device poled for conduction in the samedirection and with said second and third diodes poled for conduction inthe opposite direction.

1. In an electric spark ingition system for a plurality of gas burners,the combination of: a pair of power supply terminals for connection toan a.c. power source; and a plurality of spark ignition circuits, eachcomprising: a voltage multiplier having input terminals connected tosaid power supply terminals and having multiplier output terminals, apulsing circuit having input terminals for connection to a voltagesource and providing a pulse output to ignition electrodes of a gasburner, and electric circuit means connecting said pulsing unit inputterminals to said multiplier output terminals with a unidirectionalconducting device in circuit between one multiplier output terminal andthe corresponding pulsing circuit input terminal.
 2. A system as definedin claim 1 wherein each of said voltage multipliers is a voltagequadrupler.
 3. A system as defined in claim 1 including three of saidspark ignition circuits.
 4. A system as defined in claim 3 wherein eachof said voltage multipliers is a voltage quadrupler.
 5. A system asdefined in claim 1 wherein each of said voltage multipliers includes: afirst capacitor and a first diode connected in series at a firstjunction between one of said power supply terminals and said onemultiplier output terminal, a second capacitor connected between saidone multiplier output terminal and the other of said power supplyterminals, a second diode connected between said first junction and saidother power supply terminal, a third capacitor and a third diodeconnected in series at a second junction between said one power supplyterminal and the other of said multiplier output terminals, and a fourthdiode connected between said second junction and said other power supplyterminal, with said first and fourth diodes and said unidirectionalconducting device poled for conduction in the same direction and withsaid second and third diodes poled for conduction in the oppositedirection.